Average Speed Calculator
If a trip consists of several legs with varying distances and times, the average speed of the entire trip is not simply the average of the individual velocities of each leg. Instead, the average speed equals the total distance traveled divided by the total time elapsed.
You can use this online calculator to compute average speed for a journey that has several stages. Some sample problems are also worked out below.
Example Average Speed Problem #1Marta spends 1 hour and 20 minutes driving 90 miles along the freeway. When she enters a small town, it takes her 40 minutes to drive 15 miles into the countryside. What is her average speed for the entire trip?
Since her total distance is 105 miles and her total time is 2 hours, her average speed is 105/2 miles per hour. This works out to 52.5 miles per hour.
Notice that if you simply average the individual speeds of each leg in this example, you will get a result that is too low. On the first leg of her trip she drives at a speed of 67.5 mph, and on the second leg of her trip she drives 22.5 mph. The average of 67.5 and 22.5 is 45, which is not the correct answer.
Example Average Speed Problem #2Damon jogs two miles in 20 minutes, walks three miles in 50 minutes, and finally jogs another mile in 25 minutes. What is is average speed traveling six miles on foot?
Since his total distance is 6 miles and his total time is 95 minutes, his average speed is 6/95 miles per minute, or 0.06316 miles per minute. This is equivalent to 15.833 minutes per mile, and 3.789 miles per hour.
Example Average Speed Problem #3Bob drives 100 km per hour for 45 minutes, then drives 80 km per hour for 1 hour and 15 minutes. What is his average speed over the two-hour drive?
In this example, you have to work backard to find the distance of each segment. The first segment covers 100*(45/60) = 75 km. The second segment lasts 75 minutes and covers 80*(75/60) = 100 km. Thus the total distance is 175 km. The average speed is 175/2 = 87.5 km per hour.
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